The present invention relates to an apparatus and method of laser treatment of subsurface cutaneous tissue for the purpose of effecting a tightening of the skin and reducing wrinkles without significantly altering the epidermis.
Pulsed CO.sub.2 lasers, erbium lasers, holmium lasers, and other infrared lasers are being used clinically to remove the epidermis and superficial reticular dermis for the purpose of laser resurfacing. Besides removing the superficial layers, there is often a significant contraction of the skin associated with these laser resurfacing technologies. This skin tightening is due to sufficient, but not excessive dermal collagen heating by the laser, and it is as important to patient satisfaction as the more youthful epidermis (skin surface) appearance achieved by laser resurfacing.
Unfortunately, in order to achieve this skin tightening, it has been necessary to remove the epidermis with the laser. This results in a raw skin surface that is unsightly, and that requires extensive wound care for weeks. Attempts to reduce these unwanted morbidities by using lasers for resurfacing that do not have as much collateral thermal damage result in inadequate tightening of the skin. For example, a pulsed CO.sub.2 laser of 100 microseconds or so duration (e.g., Tru-Pulse, Tissue Technologies, Inc., Albuquerque, N. Mex.) cause less postoperative erythema, swelling, and discomfort than pulsed CO.sub.2 laser of one millisecond pulse duration (e.g., Nova-Pulse, Luxar, Inc., Redmond, Wash.), but they do not tighten the skin as much as the longer-pulsed CO.sub.2 lasers.
Wrinkle removal by pulsed infrared lasers during resurfacing is a result of removal of the epidermis and reticular dermis at the same time. Skin tightening requires deeper thermal effects than wrinkle removal. Thus attempts to reduce postoperative erythema, pain and swelling by doing a more superficial resurfacing do not result in adequate skin tightening.
Prior art (e.g., U.S. Pat. Nos. 4,976,709 and 5,484,432) attempts to selectively treat subsurface collagen without damaging the surface have been primarily related to corneal treatment (laser thermal keratoplasty) for corrections of refractive errors using infrared wavelength greater than 1.8 micron. Moreover, treatment parameters identified were selected so as to avoid a cicatrix which might impair the transparency of the cornea. For example, preferred embodiments included small (&lt;2mm in diameter) spot size, short pulse duration (0.1 sec), a fluence up to 100J/CM.sup.2 and non-contact delivery means.
Contact handpieces and non-contact delivery means for laser treatment of the eye have included designs which allow for surface-sparing of the ocular tissues, but delivery of a photocoagulation to internal tissues such as the ciliary body in glaucoma management. In U.S. Pat. No. 5,514,125, for example, a contact handpiece for delivery of laser energy to the ciliary processes in glaucoma is described. It features a fiberoptic distal member separated from a focusing lens at the contact tip for the purpose of reducing scatter of the laser energy.
Controlled subsurface laser energy also can be used to remove hair, tattoos and varicose veins. A contact subsurface laser energy delivery system that can target the follicle and not damage the sebaceous glands and sweat glands and the skin between the hairs would be advantageous. Further as system for removing tattoos and treating varicose veins by the subsurface application of laser energy is desirable.